Today's large scale computer rooms typically employ human technicians which manually load magnetic data storage media (e.g. magnetic tapes) onto computer drives. With the recent advent of computer tape cassettes (i.e., as represented by the 3480 compatible system), the space requirement for physically cataloging and storing the magnetic media has decreased (due to the decreased size of these tape cassettes as compared to the more conventional magnetic tape spools).
In the above-identified copending U.S. Patent Applications, there are disclosed novel robot transport systems having particular utility in the automated archiving and retrieval of computer data tape cassettes. In particular, the robot transport systems disclosed in those copending U.S. Patent Applications allow computer tape cassettes to be moved between a tape storage facility (where individual tape cassettes are archived) and a tape drive section (composed of individual tape drive units).
According to one aspect of the present invention, rotatable tape cassette storage carousels are provided which are especially adapted for use in the automated tape cassette archiving and retrieval systems disclosed in the above-identified copending U.S. Patent Applications. In general, the storage carousels of this invention include a number of vertically stacked shelf units each having a generally horizontally oriented shelf for supporting a row of tape cassettes on edge. The stacked shelf units are positioned a predetermined radial dimension from a central support shaft which is rotatably coupled to a motor-driven pedestal. Position sensors are provided in operative association with the carousel so that its particular rotational position may be sensed by appropriate supervisory controls associated with the automated tape cassette archiving and retrieval systems (e.g., to ensure that the correct shelf unit holding a preselected tape cassette is rotated into confronting relationship to a robotic manipulator associated with the robot transport system).
As may be appreciated, the above-noted aspect of the present invention provides for the practical storage, access, and retrieval of computer tape cassettes through the use of a storage unit which requires relatively little floor space. Additional unutilized storage space, however, may exist in the interior of single carousel storage units. Thus, according to another aspect of the present invention, a single tape cassette storage unit is provided with a plurality of rotatable tape cassette storage carousels, with each carousel connected to a single, central support shaft of the storage unit which is rotatably coupled to a drive transfer mechanism.
In general, each carousel includes a number of vertically stacked shelf units each having a generally horizontally oriented shelf for supporting a row of tape cassettes on edge. The stacked shelf units of each individual carousel are positioned a predetermined radial dimension from that carousel's central support shaft, which is rotatably coupled to a drive transfer mechanism. Each carousel rotates around its own rotation axis (the carousel's rotation axis), and all the carousels revolve around the storage unit's rotation axis.
The carousels' central support shafts are positioned a predetermined radial dimension from the storage unit's central support shaft so that the carousels do not interfere with (or touch) one another or the storage unit's central support shaft. The carousels' central support shafts are rotatably coupled to a drive means (e.g., a reversible motor) via a drive transfer means (e.g., comprising gears, belts, cables, and/or the like housed or partially housed in the supporting framework of the storage unit). Position sensors may be provided in operative association with the carousels so that the position of each carousel and each carousel's particular rotational position may be sensed by appropriate supervisory controls associated with the automated tape cassette archiving and retrieval systems (e.g., to ensure that the correct shelf unit holding a preselected tape cassette is rotated into confronting relationship to a robotic manipulator associated with the robot transport system).
According to another aspect of the present invention, additional secondary shelf units are arranged at the outer periphery of the tape cassette storage unit and are rigidly connected to the storage unit's central support shaft (which is rotatably coupled to a drive transfer mechanism). These additional secondary shelf units are arranged at the outer periphery of the storage unit in the open intermediate zones defined by adjacent carousels. The additional secondary shelf units are arranged in these open areas between adjacent carousels, i.e., in the intermediate zones, so that the area occupied by a tape cassette storage unit may be optimally utilized for the storage of tape cassettes. Thus, both the outer periphery and the interior of a tape cassette storage unit may be more fully utilized for storage purposes while also allowing for rapid, efficient access and tape retrieval from the periphery of the storage unit.
Position sensors may be provided in operative association with the secondary shelf units so that their particular rotational position (e.g., with respect to the storage unit's central shaft) may be sensed by appropriate supervisory controls associated with the automated tape cassette archiving and retrieval systems (e.g., to ensure that the correct shelf unit holding a preselected tape cassette is rotated into confronting relationship to a robotic manipulator associated with the robot transport system).
As may be further appreciated, it is difficult (if not impossible) to eliminate entirely the possibility that a robotic manipulator will come into physical contact with the tape cassette storage unit during insertion/removal of a tape cassette into/from its particular location on the self. That is, while the controls may be designed so as to accurately guide the robotic manipulator relative to the tape storage units, it is usually inevitable that some misalignment between the tape storage unit and the robotic manipulator will occur. Thus, when attempting to insert/remove a tape cassette into/from the tape storage unit, the robotic manipulator may come into physical contact with the storage unit thereby causing mechanical shock and/or vibrations to occur. These mechanical shocks and/or vibrations may, moreover, be of such a magnitude that some of the tape cassettes may be dislodged physically from their shelf and thus tumble to the computer room floor. Needless to say, such an occurrence is extremely disruptive to an automated system since human intervention is then needed to re-shelve the dislodged computer tape cassettes. Therefore, any commercially acceptable tape cassette archiving and retrieval system must be capable of tolerating equipment "crashes" as may occur between the robotic manipulator and the tape cassette storage units.
Thus, according to a further aspect of this invention, the tape storage units are provided with means which serve to maintain the tape cassettes in their respective locations and thus minimize (if not eliminate) the possibility that the tape cassettes will become dislodged from their respective shelves in response to mechanical shocks and/or vibrations. The self units may therefore simply be provided with a raised forward lip extending the entire transverse length of the shelf to thereby serve as a stop member against which the tape cassettes abut. Alternatively (or conjunctively) means may be provided so as to, in effect, rearwardly displace the tape cassettes' centers of gravity. In this manner, the tape cassettes are encouraged to remain on the self (i.e., due to their centers of gravity being displaced away from the open front of the shelf) when the tape storage unit experiences mechanical shocks and/or vibrations.
Other aspects and advantages of this invention will become more clear after careful consideration is given to the detailed description of the preferred exemplary embodiment thereof which follows.